When native bulk substrates are not available or are too expensive, useful materials are often formed by heteroepitaxy on seed substrates so that the growth of thin films on substrates by heteroepitaxy becomes an important manufacturing step in the semi-conductor technology. For instance, in the field of light-emitting semiconductor devices or solar cells there is a need to grow heteroepitaxial films on substrates as sapphire or SiC to form subsequently a final semiconductor device. After transfer of the heteroepitaxial films to another substrate these films can, for instance, be used for epitaxial growth of layers used in electronic and opto-electronic applications. However, when films are formed by heteroepitaxy on substrates with a different lattice constants and different coefficients of thermal expansion as compared to the ones of the films detrimental effects on material quality of layers grown on the films are caused by misfit compressive or tensile strain and the corresponding generation of dislocations and cracks. Thus, in the art compliant substrates, including vitreous layers, have been provided between the substrates and the heteroepitaxial films in order to release misfit strains.
However, presently used methods for the relaxation of strained heteroepitaxial films often not show satisfying results with respect to the suppression of buckling and the formation of cracks, etc. Thus, it is a problem underlying the present invention to provide a method for the complete or almost complete lateral relaxation of a strained layer formed above a substrate that avoids or at least alleviates the above-mentioned defects.